An axial pump is characterized by the liquid being sucked into the impeller in axial direction and also leaving in axial direction. The kinetic energy obtained by the rotating impeller is transformed into pressure energy by help of a number of fixed vanes downstream of the impeller. Said vanes also normally serve as supporting elements in the pump housing.
The vanes mounted on the hub may have different designs depending on the type of liquid to be pumped, the head, etc. The angle between the hub and the vane is of great importance for the pump performance. In certain bigger machines such as turbines, it is common to make the vanes adjustable in order to obtain the best performance at different heads. This solution is of course very expensive and is also sensitive for pollutants.
By designing the hub with a spheric surface upon which the vanes are mounted, it is obtained that different vane angles may be chosen without the need to change the vane itself.
The purpose of the invention is to obtain an impeller which is easy an inexpensive to produce and possible to adapt for different types of liquids and operation conditions.